Zotac are a very good company which don't mind you installing a after market cooler on the GPU. (I.E Waterblock or HSF) Without voiding the warranty, as long as you return the product in it's original factory state.

I would go for the GTX 670 as you can overclock these beyond GTX 680 performance.

If you're keen on the green team, then I'd vote 670, as TG says, good oc headroom. But, I'd personally go for a 7950 'cos they're (with the state of current drivers), quicker than both in my experience.

__________________

Comrade Woody:"I dunno, whores are a bit like cornflakes, you always regret buying the cheap ones."

The 670 is a superb card, even a reference card has a fairly quiet stock cooler with plenty of overclocking headroom.

The amd drivers have caught up for sure with games like BF3 etc, but IMO it always seems to take them a while to get them upto scratch with some of games. Latest drivers anything 7870 and up is worth considering.

I would also agree that the 7950 sounds like a pretty good deal if you're rocking at 1080p. I would think that it would be more than enough to ultra nearly everything you can throw at it. (Maybe not ultra max with all the tessellation stuff in BF3...)

I'm currently rocking with a 670 OC and sometimes I do think it's overkill. No, wait, who am I kidding?

At the time, there was no 660Ti and the gap with the 7950 was bigger since it was before all the driver updates.

To answer your original question, even clocking the nuts off a 660Ti will not put it on par with a 670. Whereas many 670s will comfortably clock up to ~ 680 stock performance.

As to whether AMDs offerings are better on a bang per buck basis, there isn't a gulf of difference between them, so just research benchmarks on the games you play. If you find the 7950 offers comparable or better rates than the 670, go for it.

TBH though it's not that big a deal if you're gaming at 19x10 - both the 670 and the 79xx cards will monster most games at that res for quite some time*.

*uber hi res texture add-ons permitting.

__________________Before you judge a man, walk a mile in his shoes; after that, who cares?! He's a mile away and you've got his shoes!

Yeah, I was pretty sure the 7950 didn't stack up to the 670, but couldn't be bothered to go digging - still a decent card though. The 7970 is a closer match, and the GHz edition out paces the 670 and competes with the 680.

Again, at 19x10 all of the above will serve you well.

BTW, I don't buy the argument that AMD cards are better because they offer more VRAM - they seem to need the extra memory to compete. Whether this is a throwback to the crappy memory controller performance shared by their CPUs... I don't know, but this isn't a fanboy argument - I'll quite happily swap between AMD and Nvidia when upgrading - just get the most for your money.

__________________Before you judge a man, walk a mile in his shoes; after that, who cares?! He's a mile away and you've got his shoes!